The present invention relates in general to a variable conductance touch sensor or transducer associated with the keys of a keyboard electronic musical instrument. More particularly, this invention pertains to an electronic musical instrument employing the aforesaid transducer and including a plurality of individual selectors for selecting different audible characteristics such as vibrato and/or brilliance, and variable control means that is settable for delimiting the effective range of the selection means.
In the prior art there is shown a key contact system for electronic organs employing a variable conductance element. See, for example, the Lester U.S. Pat. No. 2,848,920. This prior art structure basically discloses the use of spaced conductive bars which are bridged by a variable conductance element when the element contacts these bars. Until the bars are bridged there is no electrical path provided and there is no instrument output. When the bars are bridged the conductance between the bars is immediately variable in accordance with applied pressure. This sensor arrangement is used to control volume and there is no "deadband" of applied pressure over which a normal volume output occurs. Instead, each time a slightly different pressure is applied a different volume output occurs.
Accordingly, it is the purpose of the present invention to overcome this problem and provide in accordance with one aspect of this invention, an instrument wherein a note can be played upon the application of a first minimum predetermined pressure and one or more audible characteristics can be introduced upon the application of a pressure in excess of a second higher predetermined threshold pressure. With the system of this invention there is provided a deadband over which normal playing occurs. It is only when the musician desires to introduce a previously selectable audible characteristic that the note is played harder to introduce that characteristic in a variable manner in accordance with applied pressure.
Another object of the present invention is to provide in association with the touch sensor arrangement of this invention, selection means for selecting one or more of a plurality of different audible characteristics that may be introduced by selection thereof. In addition, there may also be provided in association with the selection means a variable control means that may be movable through different settings by the musician to limit the operating effectiveness of the touch sensor arrangement. This variable control means may be a single control common to all audible characteristics or there may be provided separate variable control for each audible characteristic.